Blood gases, arterial, cord

Alphabetical Test listing

Blood gases, arterial, cord-203

  
Blood gases, arterial, cord
  
203
  
82803.1
  
GCA
  
pH
pCO2
pO2
HCO3
Base excess
O2 saturation
  

Cord blood gases can provide valuable objective evidence of the metabolic condition of neonates at the moment of birth.

  

For inpatients ONLY

  
Cord blood
  

Heparinized blood gas syringe

  
2.0 mL
  
1.0 mL
  

To obtain fetal blood for acid-base analysis from the in vivo placenta and cord:

  1. Double clamp a 10 to 20 cm segment of umbilical cord as soon as possible after delivery
    1. Delay in clamping may affect pH and gas values due to gaseous diffusion and continuing metabolism.
  2. Draw blood from the umbilical artery into a heparinized blood gas syringe
  3. Transport the syringe  to the laboratory immediately
  

Do not spin and do not open prior to analysis

  

Blood gas syringe

Remove the needle from syringe prior to sending to lab

  

Ambient

Transport to the lab immediately after collection

  
  • Clotted specimen
  • Improper labels (unlabeled or mislabeled)
  • Leaking container resulting in compromised specimen
  • Quantity not sufficient (QNS)
  
AHL - Chemistry: C
  
Daily
  
1 day
  

Ion Selective Electrodes

  
pH 7.15 - 7.45
pCO2 32.0 - 66.0 mm/Hg
pO2 6.0 - 30.00 mm/Hg
HCO3 21 - 28 mmol/L
Base excess -6 to 2
O2 Sat 6 - 30%
  
pH < 7.00
HCO3 < 15 or > 40 mmol/L
Base excess <= -16
  

The pH, PCO2, PO2 are measured, whereas bicarbonate concentration, percentage oxygen saturation, and base excess (or deficit) are calculated. The most useful values for interpretation of fetal-newborn condition and prognosis are the pH and base excess (or deficit).

Sampling umbilical artery blood is preferable to sampling umbilical vein blood as the arterial pH and base deficit provide the most accurate information on fetal acid-base status and correlate best with newborn morbidity. This is because umbilical arterial blood primarily reflects fetal metabolism while venous blood primarily reflects placental functions.

Some clinicians prefer to obtain two samples, one from the artery and the other from the vein. If both vessels are sampled, the median arteriovenous pH difference is 0.09 (range 0.02 to 0.49).

One advantage to sampling both vein and artery is that the ability to compare both sets of values makes it clearer which set of values reflects the vein versus the artery. If only one sample from one vessel is collected, it is not necessarily readily apparent from the values whether the sample reflects the artery or the vein.

  
82805
  
05/23/2022
  
05/10/2024
  
01/04/2024